The present invention relates to a method of forming a graphene layer on a carbon-containing semiconductor layer, and a structure obtained by the same.
Graphene is a monolayer of a two-dimensional sheet of carbon atoms. A graphene layer has a thickness of about 0.34 nm, i.e., which is approximately the atomic diameter of a single carbon atom. Graphene provides excellent in-plane conductivity. Semiconductor devices employing graphene have been suggested in the art to provide high-density and high-switching-speed semiconductor circuits.
To enable mass manufacturing of such semiconductor devices, it is desirable to grow graphene on commercially available 200 mm or 300 mm semiconductor substrates for compatibility with manufacturing at modern microelectronic fabrication facilities. While it is known that a graphene layer may be grown by direct epitaxial deposition of carbon atoms on, i.e., addition of carbon atoms onto the surface of, a single crystalline silicon carbide (SiC) substrate having a (0001) surface orientation, such silicon carbide substrates are not commercially available at a diameter greater than 4 (or 5) inches at the present time. Such unavailability of silicon carbide (SiC) substrates currently makes it impossible to provide a 200 mm substrate or a 300 mm substrate containing a graphene layer.
Prior attempts to grow a single crystalline silicon carbide layer on a single crystalline silicon substrate have been unsuccessful because of the large lattice mismatch between a silicon crystal and a silicon carbide crystal. In other words, the epitaxial strain of the silicon carbide layer was high enough to destroy the single crystalline alignment between the underlying silicon crystal and the deposited silicon carbide layer such that the deposited silicon carbide layer is rendered polycrystalline. That is, the high stress that exists due to lattice mismatch between the silicon and silicon carbide lattices produces polycrystalline non-commensurate growth of silicon carbide on silicon. Attempts to grow a graphene layer by epitaxial deposition of carbon on such a polycrystalline silicon carbide layer is futile because formation of a graphene layer by epitaxial growth of carbon requires a single crystalline (0001) silicon carbide surface.